How many different positive, six-digit integers can be formed using the digits 2, 2, 5, 5, 9 and 9?
2, 2, 5, 5, 9, 9==6 digits ==6!/2!.2!.2!==90 permutations as follows:
[(2, 2, 5, 5, 9, 9), (2, 2, 5, 9, 5, 9), (2, 2, 5, 9, 9, 5), (2, 2, 9, 5, 5, 9), (2, 2, 9, 5, 9, 5), (2, 2, 9, 9, 5, 5), (2, 5, 2, 5, 9, 9), (2, 5, 2, 9, 5, 9), (2, 5, 2, 9, 9, 5), (2, 5, 5, 2, 9, 9), (2, 5, 5, 9, 2, 9), (2, 5, 5, 9, 9, 2), (2, 5, 9, 2, 5, 9), (2, 5, 9, 2, 9, 5), (2, 5, 9, 5, 2, 9), (2, 5, 9, 5, 9, 2), (2, 5, 9, 9, 2, 5), (2, 5, 9, 9, 5, 2), (2, 9, 2, 5, 5, 9), (2, 9, 2, 5, 9, 5), (2, 9, 2, 9, 5, 5), (2, 9, 5, 2, 5, 9), (2, 9, 5, 2, 9, 5), (2, 9, 5, 5, 2, 9), (2, 9, 5, 5, 9, 2), (2, 9, 5, 9, 2, 5), (2, 9, 5, 9, 5, 2), (2, 9, 9, 2, 5, 5), (2, 9, 9, 5, 2, 5), (2, 9, 9, 5, 5, 2), (5, 2, 2, 5, 9, 9), (5, 2, 2, 9, 5, 9), (5, 2, 2, 9, 9, 5), (5, 2, 5, 2, 9, 9), (5, 2, 5, 9, 2, 9), (5, 2, 5, 9, 9, 2), (5, 2, 9, 2, 5, 9), (5, 2, 9, 2, 9, 5), (5, 2, 9, 5, 2, 9), (5, 2, 9, 5, 9, 2), (5, 2, 9, 9, 2, 5), (5, 2, 9, 9, 5, 2), (5, 5, 2, 2, 9, 9), (5, 5, 2, 9, 2, 9), (5, 5, 2, 9, 9, 2), (5, 5, 9, 2, 2, 9), (5, 5, 9, 2, 9, 2), (5, 5, 9, 9, 2, 2), (5, 9, 2, 2, 5, 9), (5, 9, 2, 2, 9, 5), (5, 9, 2, 5, 2, 9), (5, 9, 2, 5, 9, 2), (5, 9, 2, 9, 2, 5), (5, 9, 2, 9, 5, 2), (5, 9, 5, 2, 2, 9), (5, 9, 5, 2, 9, 2), (5, 9, 5, 9, 2, 2), (5, 9, 9, 2, 2, 5), (5, 9, 9, 2, 5, 2), (5, 9, 9, 5, 2, 2), (9, 2, 2, 5, 5, 9), (9, 2, 2, 5, 9, 5), (9, 2, 2, 9, 5, 5), (9, 2, 5, 2, 5, 9), (9, 2, 5, 2, 9, 5), (9, 2, 5, 5, 2, 9), (9, 2, 5, 5, 9, 2), (9, 2, 5, 9, 2, 5), (9, 2, 5, 9, 5, 2), (9, 2, 9, 2, 5, 5), (9, 2, 9, 5, 2, 5), (9, 2, 9, 5, 5, 2), (9, 5, 2, 2, 5, 9), (9, 5, 2, 2, 9, 5), (9, 5, 2, 5, 2, 9), (9, 5, 2, 5, 9, 2), (9, 5, 2, 9, 2, 5), (9, 5, 2, 9, 5, 2), (9, 5, 5, 2, 2, 9), (9, 5, 5, 2, 9, 2), (9, 5, 5, 9, 2, 2), (9, 5, 9, 2, 2, 5), (9, 5, 9, 2, 5, 2), (9, 5, 9, 5, 2, 2), (9, 9, 2, 2, 5, 5), (9, 9, 2, 5, 2, 5), (9, 9, 2, 5, 5, 2), (9, 9, 5, 2, 2, 5), (9, 9, 5, 2, 5, 2), (9, 9, 5, 5, 2, 2)] >Total distinct permutations = 90
